Question

Write a program that takes a file as input and checks whether or not the content of the file is balanced. In the context of this assignment “balanced” means that your program will check to make sure that for each left bracket there is a closing right bracket.

Examples:

            [ ( ) ] { } à balanced.

            [ ( ] ) { } à unbalanced.

Here is the list of brackets/braces that program must support:

• (: left parentheses (NOT smiley face).
• ): right parentheses (again NOT sad face)
• [: left square bracket
• ]: right square bracket
• {: left curly bracket
• }: right curly bracket
• <: left angle bracket
• >: right angle bracket

Have to implement this program using the Stack data structure. Feel free to use either ArrayStack or LinkedStack from the textbook or build your own class.

Other requirements:

• File input/output:
  • program should detect empty files and throw an exception displaying the following message: “This file is empty + fileName”.
  • program should detect invalid file names and throw an exception displaying the following message: “File doesn’t exist + fileName”.
• After you process the input file you have to display the content of the file as well as a message saying either “balanced” or “unbalanced”.
• Print the line number where the unbalanced bracket is found.
• You will need at least the following three classes:
  • Driver: main
  • ArrayStack or LinkedStack: data structure
  • SimpleParser: read the file, check balance, …
  • program should be able to read the file name from the command prompt:
    • Example: java Driver Foo.java

using java

Answer 1

Output:


code:
import java.io.BufferedReader;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.util.Stack;

public class BalancedParantesisSolution {

   private boolean isInPair(Character character1, Character character2) {

       return (character1.equals('(') && character2.equals(')')) || //
               (character1.equals('{') && character2.equals('}')) || //
               (character1.equals('[') && character2.equals(']')) || //
               (character1.equals('<') && character2.equals('>'));
   }

public static boolean isParenthesisBalanced(char[] exp) {

       Stack<Character> stack = new Stack<>();

       for (int i = 0; i < exp.length; i++) {

           if (exp[i] == '{' || exp[i] == '(' || exp[i] == '[' || exp[i] == '<') {
               stack.push(exp[i]);
           }

           if (exp[i] == '}' || exp[i] == ')' || exp[i] == ']' || exp[i] == '>') {
               if (stack.isEmpty()) {
                   return false;
               } else if (!isInPair(stack.pop(), exp[i])) {
                   return false;
               }
           }

       }

       return stack.isEmpty();
   }

   public static void main(String[] args) {
       if (args.length == 0) {
           System.out.println("Usage : \n java -jar driver.jar fileToBeparsed.txt");
       } else {
           String fileName = args[0];

           File file = new File(fileName);

           try (BufferedReader br = new BufferedReader(new FileReader(file))) {

               if (file.length() == 0) {
                   System.out.println("This file is empty " + fileName);
                   return;
               }
               String currentLine;

               while ((currentLine = br.readLine()) != null) {

                   System.out.println(currentLine + " is " + //
                   (isParenthesisBalanced(currentLine.replaceAll(" ", "").toCharArray()) ? "balanced" : "unbalanced"));
               }

           } catch (FileNotFoundException e) {
               System.out.println("File doesn’t exist " + fileName);
           } catch (IOException e) {
               System.out.println("Error reading file " + fileName);
           }

       }

   }

}

<terminated BalancedParantesisSolution Java Application] [) < is unbalanced [( ) ) { } is unbalanced

<terminated BalancedParantesisSolution Java Application] [) < is unbalanced [( ) ) { } is unbalanced